/*
 * GStreamer
 * Copyright (C) 2008 Filippo Argiolas <filippo.argiolas@gmail.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#if HAVE_CONFIG_H
#include "config.h"
#endif

#include <gst/gl/gstglconfig.h>

#include "../gstgleffects.h"
#include "gstgleffectssources.h"
#include <math.h>

/* A common file for sources is needed since shader sources can be
 * generic and reused by several effects */

/* FIXME */
/* Move sooner or later into single .frag .vert files and either bake
 * them into a c file at compile time or load them at run time */


/* fill a normalized and zero centered gaussian vector for separable
 * gaussian convolution */

void
fill_gaussian_kernel (float *kernel, int size, float sigma)
{
  int i;
  float sum;
  int l;

  /* need an odd sized vector to center it at zero */
  g_return_if_fail ((size % 2) != 0);

  sum = 0.0;
  l = (size - 1) / 2;

  for (i = 0; i < size; i++) {
    kernel[i] = expf (-0.5 * pow ((i - l) / sigma, 2.0));
    sum += kernel[i];
  }

  for (i = 0; i < size; i++) {
    kernel[i] /= sum;
  }
}

/* *INDENT-OFF* */

/* Mirror effect */
const gchar *mirror_fragment_source_opengl =
  "uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = gl_TexCoord[0].xy;"
  "  vec2 normcoord;"
  "  normcoord = texturecoord - 0.5;"
  "  normcoord.x *= sign (normcoord.x);"
  "  texturecoord = normcoord + 0.5;"
  "  vec4 color = texture2D (tex, texturecoord);"
  "  gl_FragColor = color * gl_Color;"
  "}";

const gchar *mirror_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = v_texcoord.xy;"
  "  float normcoord = texturecoord.x - 0.5;"
  "  normcoord *= sign (normcoord);"
  "  texturecoord.x = normcoord + 0.5;"
  "  gl_FragColor = texture2D (tex, texturecoord);"
  "}";

/* Squeeze effect */
const gchar *squeeze_fragment_source_opengl =
  "uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = gl_TexCoord[0].xy;"
  "  vec2 normcoord = texturecoord - 0.5;"
  "  float r = length (normcoord);"
  "  r = pow(r, 0.40)*1.3;"
  "  normcoord = normcoord / r;"
  "  texturecoord = (normcoord + 0.5);"
  "  gl_FragColor = texture2D (tex, texturecoord);"
  "}";

const gchar *squeeze_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = v_texcoord.xy;"
  "  vec2 normcoord = texturecoord - 0.5;"
  "  float r = length (normcoord);"
  "  r = pow(r, 0.40)*1.3;"
  "  normcoord = normcoord / r;"
  "  texturecoord = (normcoord + 0.5);"
  "  gl_FragColor = texture2D (tex, texturecoord);"
  "}";

/* Stretch Effect */
const gchar *stretch_fragment_source_opengl =
  "uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = gl_TexCoord[0].xy;"
  "  vec2 normcoord;"
  "  normcoord = texturecoord - 0.5;"
  "  float r = length (normcoord);"
  "  normcoord *= 2.0 - smoothstep(0.0, 0.35, r);"
  "  texturecoord = normcoord + 0.5;"
  "  vec4 color = texture2D (tex, texturecoord);"
  "  gl_FragColor = color * gl_Color;"
  "}";

const gchar *stretch_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "void main () {"
	"  vec2 texturecoord = v_texcoord.xy;"
  "  vec2 normcoord;"
  "  normcoord = texturecoord - 0.5;"
  "  float r = length (normcoord);"
  "  normcoord *= 2.0 - smoothstep(0.0, 0.35, r);"
  "  texturecoord = normcoord + 0.5;"
  "  gl_FragColor = texture2D (tex, texturecoord);"
  "}";

/* Light Tunnel effect */
const gchar *tunnel_fragment_source_opengl =
  "uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = gl_TexCoord[0].xy;"
  "  vec2 normcoord;"
  /* little trick with normalized coords to obtain a circle with
   * rect textures */
  "  normcoord = (texturecoord - 0.5);"
  "  float r = length(normcoord);"
  "  normcoord *= clamp (r, 0.0, 0.275) / r;"
  "  texturecoord = normcoord + 0.5;"
  "  vec4 color = texture2D (tex, texturecoord); "
  "  gl_FragColor = color;"
  "}";

const gchar *tunnel_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = v_texcoord.xy;"
  "  vec2 normcoord;"
  /* little trick with normalized coords to obtain a circle with
   * rect textures */
  "  normcoord = (texturecoord - 0.5);"
  "  float r = length(normcoord);"
  "  normcoord *= clamp (r, 0.0, 0.275) / r;"
  "  texturecoord = normcoord + 0.5;"
  "  gl_FragColor = texture2D (tex, texturecoord);"
  "}";

/* FishEye effect */
const gchar *fisheye_fragment_source_opengl =
  "uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = gl_TexCoord[0].xy;"
  "  vec2 normcoord;"
  "  normcoord = texturecoord - 0.5;"
  "  float r = length (normcoord);"
  "  normcoord *= r * sqrt(2.0);"
  "  texturecoord = normcoord + 0.5;"
  "  vec4 color = texture2D (tex, texturecoord);"
  "  gl_FragColor = color;"
  "}";

const gchar *fisheye_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = v_texcoord.xy;"
  "  vec2 normcoord;"
  "  normcoord = texturecoord - 0.5;"
  "  float r = length (normcoord);"
  "  normcoord *= r * sqrt(2);"
  "  texturecoord = normcoord + 0.5;"
  "  gl_FragColor = texture2D (tex, texturecoord);"
  "}";

/* Twirl effect */
const gchar *twirl_fragment_source_opengl =
  "uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = gl_TexCoord[0].xy;"
  "  vec2 normcoord;"
  "  normcoord = texturecoord - 0.5;"
  "  float r = length (normcoord);"
  /* calculate rotation angle: maximum (about pi/2) at the origin and
   * gradually decrease it up to 0.6 of each quadrant */
  "  float phi = (1.0 - smoothstep (0.0, 0.3, r)) * 1.6;"
  /* precalculate sin phi and cos phi, save some alu */
  "  float s = sin(phi);"
  "  float c = cos(phi);"
  /* rotate */
  "  normcoord *= mat2(c, s, -s, c);"
  "  texturecoord = normcoord + 0.5;"
  "  vec4 color = texture2D (tex, texturecoord); "
  "  gl_FragColor = color;"
  "}";

const gchar *twirl_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
	"uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = v_texcoord.xy;"
  "  vec2 normcoord;"
  "  normcoord = texturecoord - 0.5;"
  "  float r = length (normcoord);"
  /* calculate rotation angle: maximum (about pi/2) at the origin and
   * gradually decrease it up to 0.6 of each quadrant */
  "  float phi = (1.0 - smoothstep (0.0, 0.3, r)) * 1.6;"
  /* precalculate sin phi and cos phi, save some alu */
  "  float s = sin(phi);"
  "  float c = cos(phi);"
  /* rotate */
  "  normcoord *= mat2(c, s, -s, c);"
  "  texturecoord = normcoord + 0.5;"
  "  gl_FragColor = texture2D (tex, texturecoord);"
  "}";

/* Bulge effect */
const gchar *bulge_fragment_source_opengl =
  "uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = gl_TexCoord[0].xy;"
  "  vec2 normcoord;"
  "  normcoord = texturecoord - 0.5;"
  "  float r =  length (normcoord);"
  "  normcoord *= smoothstep (-0.05, 0.25, r);"
  "  texturecoord = normcoord + 0.5;"
  "  vec4 color = texture2D (tex, texturecoord);"
  "  gl_FragColor = color;"
  "}";

const gchar *bulge_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = v_texcoord.xy;"
  "  vec2 normcoord;"
  "  normcoord = texturecoord - 0.5;"
  "  float r =  length (normcoord);"
  "  normcoord *= smoothstep (-0.05, 0.25, r);"
  "  texturecoord = normcoord + 0.5;"
  "  gl_FragColor = texture2D (tex, texturecoord);"
  "}";

/* Square Effect */
const gchar *square_fragment_source_opengl =
  "uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = gl_TexCoord[0].xy;"
  "  vec2 normcoord;"
  "  normcoord = texturecoord - 0.5;"
  "  float r = length (normcoord);"
  "  normcoord *= 1.0 + smoothstep(0.125, 0.25, abs(normcoord));"
  "  normcoord /= 2.0; /* zoom amount */"
  "  texturecoord = normcoord + 0.5;"
  "  vec4 color = texture2D (tex, texturecoord);"
  "  gl_FragColor = color * gl_Color;"
  "}";

const gchar *square_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = v_texcoord.xy;"
  "  vec2 normcoord;"
  "  normcoord = texturecoord - 0.5;"
  "  float r = length (normcoord);"
  "  normcoord *= 1.0 + smoothstep(0.125, 0.25, abs(normcoord));"
  "  normcoord /= 2.0; /* zoom amount */"
  "  texturecoord = normcoord + 0.5;"
  "  gl_FragColor = texture2D (tex, texturecoord);"
  "}";

const gchar *luma_threshold_fragment_source_opengl =
  "uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = gl_TexCoord[0].st;"
  "  vec4 color = texture2D(tex, texturecoord);"
  "  float luma = dot(color.rgb, vec3(0.2125, 0.7154, 0.0721));"    /* BT.709 (from orange book) */
  "  gl_FragColor = vec4 (vec3 (smoothstep (0.30, 0.50, luma)), color.a);"
  "}";

const gchar *luma_threshold_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "void main () {"
  "  vec2 texturecoord = v_texcoord.xy;"
  "  vec4 color = texture2D(tex, texturecoord);"
  "  float luma = dot(color.rgb, vec3(0.2125, 0.7154, 0.0721));"    /* BT.709 (from orange book) */
  "  gl_FragColor = vec4 (vec3 (smoothstep (0.30, 0.50, luma)), color.a);"
  "}";

const gchar *sep_sobel_length_fragment_source_opengl =
  "uniform sampler2D tex;"
  "uniform bool invert;"
  "void main () {"
  "  vec4 g = texture2D (tex, gl_TexCoord[0].st);"
  /* restore black background with grey edges */
  "  g -= vec4(0.5, 0.5, 0.0, 0.0);"
  "  float len = length (g);"
  /* little trick to avoid IF operator */
  /* TODO: test if a standalone inverting pass is worth */
  "  gl_FragColor = abs(vec4(vec3(float(invert) - len), 1.0));"
  "}";

const gchar *sep_sobel_length_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "uniform bool invert;"
  "void main () {"
  "  vec4 g = texture2D (tex, v_texcoord.xy);"
  /* restore black background with grey edges */
  "  g -= vec4(0.5, 0.5, 0.0, 0.0);"
  "  float len = length (g);"
  /* little trick to avoid IF operator */
  /* TODO: test if a standalone inverting pass is worth */
  "  gl_FragColor = abs(vec4(vec3(float(invert) - len), 1.0));"
  "}";

const gchar *desaturate_fragment_source_opengl =
  "uniform sampler2D tex;"
  "void main () {"
  "  vec4 color = texture2D (tex, gl_TexCoord[0].st);"
  "  float luma = dot(color.rgb, vec3(0.2125, 0.7154, 0.0721));"
  "  gl_FragColor = vec4(vec3(luma), color.a);"
  "}";

const gchar *desaturate_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "void main () {"
  "  vec4 color = texture2D (tex, v_texcoord.xy);"
  "  float luma = dot(color.rgb, vec3(0.2125, 0.7154, 0.0721));"
  "  gl_FragColor = vec4(vec3(luma), color.a);"
  "}";

const gchar *sep_sobel_hconv3_fragment_source_opengl =
  "uniform sampler2D tex;"
  "uniform float width;"
  "void main () {"
  "  float w = 1.0 / width;"
  "  vec2 texturecoord[3];"
  "  texturecoord[1] = gl_TexCoord[0].st;"
  "  texturecoord[0] = texturecoord[1] - vec2(w, 0.0);"
  "  texturecoord[2] = texturecoord[1] + vec2(w, 0.0);"
  "  float grad_kern[3];"
  "  grad_kern[0] = 1.0;"
  "  grad_kern[1] = 0.0;"
  "  grad_kern[2] = -1.0;"
  "  float blur_kern[3];"
  "  blur_kern[0] = 0.25;"
  "  blur_kern[1] = 0.5;"
  "  blur_kern[2] = 0.25;"
  "  int i;"
  "  vec4 sum = vec4 (0.0);"
  "  for (i = 0; i < 3; i++) { "
  "    vec4 neighbor = texture2D(tex, texturecoord[i]); "
  "    sum.r = neighbor.r * blur_kern[i] + sum.r;"
  "    sum.g = neighbor.g * grad_kern[i] + sum.g;"
  "  }"
  "  gl_FragColor = sum + vec4(0.0, 0.5, 0.0, 0.0);"
  "}";

const gchar *sep_sobel_hconv3_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "uniform float width;"
  "void main () {"
  "  float w = 1.0 / width;"
  "  vec2 texturecoord[3];"
  "  texturecoord[1] = v_texcoord.xy;"
  "  texturecoord[0] = texturecoord[1] - vec2(w, 0.0);"
  "  texturecoord[2] = texturecoord[1] + vec2(w, 0.0);"
  "  float grad_kern[3];"
  "  grad_kern[0] = 1.0;"
  "  grad_kern[1] = 0.0;"
  "  grad_kern[2] = -1.0;"
  "  float blur_kern[3];"
  "  blur_kern[0] = 0.25;"
  "  blur_kern[1] = 0.5;"
  "  blur_kern[2] = 0.25;"
  "  int i;"
  "  vec4 sum = vec4 (0.0);"
  "  for (i = 0; i < 3; i++) { "
  "    vec4 neighbor = texture2D(tex, texturecoord[i]); "
  "    sum.r = neighbor.r * blur_kern[i] + sum.r;"
  "    sum.g = neighbor.g * grad_kern[i] + sum.g;"
  "  }"
  "  gl_FragColor = sum + vec4(0.0, 0.5, 0.0, 0.0);"
  "}";

const gchar *sep_sobel_vconv3_fragment_source_opengl =
  "uniform sampler2D tex;"
  "uniform float height;"
  "void main () {"
  "  float h = 1.0 / height;"
  "  vec2 texturecoord[3];"
  "  texturecoord[1] = gl_TexCoord[0].st;"
  "  texturecoord[0] = texturecoord[1] - vec2(0.0, h);"
  "  texturecoord[2] = texturecoord[1] + vec2(0.0, h);"
  "  float grad_kern[3];"
  "  grad_kern[0] = 1.0;"
  "  grad_kern[1] = 0.0;"
  "  grad_kern[2] = -1.0;"
  "  float blur_kern[3];"
  "  blur_kern[0] = 0.25;"
  "  blur_kern[1] = 0.5;"
  "  blur_kern[2] = 0.25;"
  "  int i;"
  "  vec4 sum = vec4 (0.0);"
  "  for (i = 0; i < 3; i++) { "
  "    vec4 neighbor = texture2D(tex, texturecoord[i]); "
  "    sum.r = neighbor.r * grad_kern[i] + sum.r;"
  "    sum.g = neighbor.g * blur_kern[i] + sum.g;"
  "  }"
  "  gl_FragColor = sum + vec4(0.5, 0.0, 0.0, 0.0);"
  "}";

const gchar *sep_sobel_vconv3_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "uniform float height;"
  "void main () {"
  "  float h = 1.0 / height;"
  "  vec2 texturecoord[3];"
  "  texturecoord[1] = v_texcoord.xy;"
  "  texturecoord[0] = texturecoord[1] - vec2(0.0, h);"
  "  texturecoord[2] = texturecoord[1] + vec2(0.0, h);"
  "  float grad_kern[3];"
  "  grad_kern[0] = 1.0;"
  "  grad_kern[1] = 0.0;"
  "  grad_kern[2] = -1.0;"
  "  float blur_kern[3];"
  "  blur_kern[0] = 0.25;"
  "  blur_kern[1] = 0.5;"
  "  blur_kern[2] = 0.25;"
  "  int i;"
  "  vec4 sum = vec4 (0.0);"
  "  for (i = 0; i < 3; i++) { "
  "    vec4 neighbor = texture2D(tex, texturecoord[i]); "
  "    sum.r = neighbor.r * grad_kern[i] + sum.r;"
  "    sum.g = neighbor.g * blur_kern[i] + sum.g;"
  "  }"
  "  gl_FragColor = sum + vec4(0.5, 0.0, 0.0, 0.0);"
  "}";

/* horizontal convolution 7x7 */
const gchar *hconv7_fragment_source_opengl =
  "uniform sampler2D tex;"
  "uniform float kernel[7];"
  "uniform float gauss_width;"
  "void main () {"
  "  float w = 1.0 / gauss_width;"
  "  vec2 texturecoord[7];"
  "  texturecoord[3] = gl_TexCoord[0].st;"
  "  texturecoord[2] = texturecoord[3] - vec2(w, 0.0);"
  "  texturecoord[1] = texturecoord[2] - vec2(w, 0.0);"
  "  texturecoord[0] = texturecoord[1] - vec2(w, 0.0);"
  "  texturecoord[4] = texturecoord[3] + vec2(w, 0.0);"
  "  texturecoord[5] = texturecoord[4] + vec2(w, 0.0);"
  "  texturecoord[6] = texturecoord[5] + vec2(w, 0.0);"
  "  int i;"
  "  vec4 sum = vec4 (0.0);"
  "  for (i = 0; i < 7; i++) { "
  "    vec4 neighbor = texture2D(tex, texturecoord[i]); "
  "    sum += neighbor * kernel[i];"
  "  }"
  "  gl_FragColor = sum;"
  "}";

const gchar *hconv7_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "uniform float kernel[7];"
  "uniform float gauss_width;"
  "void main () {"
  "  float w = 1.0 / gauss_width;"
  "  vec2 texturecoord[7];"
  "  texturecoord[3] = v_texcoord.xy;"
  "  texturecoord[2] = texturecoord[3] - vec2(w, 0.0);"
  "  texturecoord[1] = texturecoord[2] - vec2(w, 0.0);"
  "  texturecoord[0] = texturecoord[1] - vec2(w, 0.0);"
  "  texturecoord[4] = texturecoord[3] + vec2(w, 0.0);"
  "  texturecoord[5] = texturecoord[4] + vec2(w, 0.0);"
  "  texturecoord[6] = texturecoord[5] + vec2(w, 0.0);"
  "  int i;"
  "  vec4 sum = vec4 (0.0);"
  "  for (i = 0; i < 7; i++) { "
  "    vec4 neighbor = texture2D(tex, texturecoord[i]); "
  "    sum += neighbor * kernel[i];"
  "  }"
  "  gl_FragColor = sum;"
  "}";

/* vertical convolution 7x7 */
const gchar *vconv7_fragment_source_opengl =
  "uniform sampler2D tex;"
  "uniform float kernel[7];"
  "uniform float gauss_height;"
  "void main () {"
  "  float h = 1.0 / gauss_height;"
  "  vec2 texturecoord[7];"
  "  texturecoord[3] = gl_TexCoord[0].st;"
  "  texturecoord[2] = texturecoord[3] - vec2(0.0, h);"
  "  texturecoord[1] = texturecoord[2] - vec2(0.0, h);"
  "  texturecoord[0] = texturecoord[1] - vec2(0.0, h);"
  "  texturecoord[4] = texturecoord[3] + vec2(0.0, h);"
  "  texturecoord[5] = texturecoord[4] + vec2(0.0, h);"
  "  texturecoord[6] = texturecoord[5] + vec2(0.0, h);"
  "  int i;"
  "  vec4 sum = vec4 (0.0);"
  "  for (i = 0; i < 7; i++) { "
  "    vec4 neighbor = texture2D(tex, texturecoord[i]);"
  "    sum += neighbor * kernel[i];"
  "  }"
  "  gl_FragColor = sum;"
  "}";

const gchar *vconv7_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "uniform float kernel[7];"
  "uniform float gauss_height;"
  "void main () {"
  "  float h = 1.0 / gauss_height;"
  "  vec2 texturecoord[7];"
  "  texturecoord[3] = v_texcoord.xy;"
  "  texturecoord[2] = texturecoord[3] - vec2(0.0, h);"
  "  texturecoord[1] = texturecoord[2] - vec2(0.0, h);"
  "  texturecoord[0] = texturecoord[1] - vec2(0.0, h);"
  "  texturecoord[4] = texturecoord[3] + vec2(0.0, h);"
  "  texturecoord[5] = texturecoord[4] + vec2(0.0, h);"
  "  texturecoord[6] = texturecoord[5] + vec2(0.0, h);"
  "  int i;"
  "  vec4 sum = vec4 (0.0);"
  "  for (i = 0; i < 7; i++) { "
  "    vec4 neighbor = texture2D(tex, texturecoord[i]);"
  "    sum += neighbor * kernel[i];"
  "  }"
  "  gl_FragColor = sum;"
  "}";

/* TODO: support several blend modes */
const gchar *sum_fragment_source_opengl =
  "uniform sampler2D base;"
  "uniform sampler2D blend;"
  "uniform float alpha;"
  "uniform float beta;"
  "void main () {"
  "  vec4 basecolor = texture2D (base, gl_TexCoord[0].st);"
  "  vec4 blendcolor = texture2D (blend, gl_TexCoord[0].st);"
  "  gl_FragColor = alpha * basecolor + beta * blendcolor;"
  "}";

const gchar *sum_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D base;"
  "uniform sampler2D blend;"
  "uniform float alpha;"
  "uniform float beta;"
  "void main () {"
  "  vec4 basecolor = texture2D (base, v_texcoord.xy);"
  "  vec4 blendcolor = texture2D (blend, v_texcoord.xy);"
  "  gl_FragColor = alpha * basecolor + beta * blendcolor;"
  "}";

const gchar *multiply_fragment_source_opengl =
  "uniform sampler2D base;"
  "uniform sampler2D blend;"
  "uniform float alpha;"
  "void main () {"
  "  vec4 basecolor = texture2D (base, gl_TexCoord[0].st);"
  "  vec4 blendcolor = texture2D (blend, gl_TexCoord[0].st);"
  "  gl_FragColor = (1.0 - alpha) * basecolor + alpha * basecolor * blendcolor;"
  "}";

const gchar *multiply_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D base;"
  "uniform sampler2D blend;"
  "uniform float alpha;"
  "void main () {"
  "  vec4 basecolor = texture2D (base, v_texcoord.xy);"
  "  vec4 blendcolor = texture2D (blend, v_texcoord.xy);"
  "  gl_FragColor = (1.0 - alpha) * basecolor + alpha * basecolor * blendcolor;"
  "}";

/* lut operations, map luma to tex1d, see orange book (chapter 19) */
const gchar *luma_to_curve_fragment_source_opengl =
  "uniform sampler2D tex;"
  "uniform sampler1D curve;"
  "void main () {"
  "  vec2 texturecoord = gl_TexCoord[0].st;"
  "  vec4 color = texture2D (tex, texturecoord);"
  "  float luma = dot(color.rgb, vec3(0.2125, 0.7154, 0.0721));"
  "  color = texture1D(curve, luma);"
  "  gl_FragColor = color;"
  "}";

const gchar *luma_to_curve_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "uniform sampler2D curve;"
  "void main () {"
  "  vec2 texturecoord = v_texcoord.xy;"
  "  vec4 color = texture2D (tex, texturecoord);"
  "  float luma = dot(color.rgb, vec3(0.2125, 0.7154, 0.0721));"
  "  color = texture2D (curve, vec2(luma, 0.0));"
  "  gl_FragColor = color;"
  "}";

/* lut operations, map rgb to tex1d, see orange book (chapter 19) */
const gchar *rgb_to_curve_fragment_source_opengl =
  "uniform sampler2D tex;"
  "uniform sampler1D curve;"
  "void main () {"
  "  vec4 color = texture2D (tex, gl_TexCoord[0].st);"
  "  vec4 outcolor;"
  "  outcolor.r = texture1D(curve, color.r).r;"
  "  outcolor.g = texture1D(curve, color.g).g;"
  "  outcolor.b = texture1D(curve, color.b).b;"
  "  outcolor.a = color.a;"
  "  gl_FragColor = outcolor;"
  "}";

const gchar *rgb_to_curve_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "uniform sampler2D curve;"
  "void main () {"
  "  vec4 color = texture2D (tex, v_texcoord.xy);"
  "  vec4 outcolor;"
  "  outcolor.r = texture2D (curve, vec2(color.r, 0.0)).r;"
  "  outcolor.g = texture2D (curve, vec2(color.g, 0.0)).g;"
  "  outcolor.b = texture2D (curve, vec2(color.b, 0.0)).b;"
  "  outcolor.a = color.a;"
  "  gl_FragColor = outcolor;"
  "}";

const gchar *sin_fragment_source_opengl =
  "uniform sampler2D tex;"
  "void main () {"
  "  vec4 color = texture2D (tex, vec2(gl_TexCoord[0].st));"
  "  float luma = dot(color.rgb, vec3(0.2125, 0.7154, 0.0721));"
/* calculate hue with the Preucil formula */
  "  float cosh = color.r - 0.5*(color.g + color.b);"
/* sqrt(3)/2 = 0.866 */
  "  float sinh = 0.866*(color.g - color.b);"
/* hue = atan2 h */
  "  float sch = (1.0-sinh)*cosh;"
/* ok this is a little trick I came up because I didn't find any
 * detailed proof of the Preucil formula. The issue is that tan(h) is
 * pi-periodic so the smoothstep thing gives both reds (h = 0) and
 * cyans (h = 180). I don't want to use atan since it requires
 * branching and doesn't work on i915. So take only the right half of
 * the circle where cosine is positive */
/* take a slightly purple color trying to get rid of human skin reds */
/* tanh = +-1.0 for h = +-45, where yellow=60, magenta=-60 */
  "  float a = smoothstep (0.3, 1.0, sch);"
  "  float b = smoothstep (-0.4, -0.1, sinh);"
  "  float mix = a * b;"
  "  gl_FragColor = color * mix + luma * (1.0 - mix);"
  "}";

const gchar *sin_fragment_source_gles2 =
  "#ifdef GL_ES\n"
  "precision mediump float;\n"
  "#endif\n"
  "varying vec2 v_texcoord;"
  "uniform sampler2D tex;"
  "void main () {"
  "  vec4 color = texture2D (tex, vec2(v_texcoord.xy));"
  "  float luma = dot(color.rgb, vec3(0.2125, 0.7154, 0.0721));"
/* calculate hue with the Preucil formula */
  "  float cosh = color.r - 0.5*(color.g + color.b);"
/* sqrt(3)/2 = 0.866 */
  "  float sinh = 0.866*(color.g - color.b);"
/* hue = atan2 h */
  "  float sch = (1.0-sinh)*cosh;"
/* ok this is a little trick I came up because I didn't find any
 * detailed proof of the Preucil formula. The issue is that tan(h) is
 * pi-periodic so the smoothstep thing gives both reds (h = 0) and
 * cyans (h = 180). I don't want to use atan since it requires
 * branching and doesn't work on i915. So take only the right half of
 * the circle where cosine is positive */
/* take a slightly purple color trying to get rid of human skin reds */
/* tanh = +-1.0 for h = +-45, where yellow=60, magenta=-60 */
  "  float a = smoothstep (0.3, 1.0, sch);"
  "  float b = smoothstep (-0.4, -0.1, sinh);"
  "  float mix = a * b;"
  "  gl_FragColor = color * mix + luma * (1.0 - mix);"
  "}";

const gchar *interpolate_fragment_source =
  "uniform sampler2D base;"
  "uniform sampler2D blend;"
  "void main () {"
  "vec4 basecolor = texture2D (base, gl_TexCoord[0].st);"
  "vec4 blendcolor = texture2D (blend, gl_TexCoord[0].st);"
  "vec4 white = vec4(1.0);"
  "gl_FragColor = blendcolor + (1.0 - blendcolor.a) * basecolor;"
  "}";

const gchar *texture_interp_fragment_source =
  "uniform sampler2D base;"
  "uniform sampler2D blend;"
  "uniform sampler2D alpha;"
  "void main () {"
  "  vec4 basecolor = texture2D (base, gl_TexCoord[0].st);"
  "  vec4 blendcolor = texture2D (blend, gl_TexCoord[0].st);"
  "  vec4 alphacolor = texture2D (alpha, gl_TexCoord[0].st);"
  "  gl_FragColor = (alphacolor * blendcolor) + (1.0 - alphacolor) * basecolor;"
  "}";

const gchar *difference_fragment_source =
  "uniform sampler2D saved;"
  "uniform sampler2D current;"
  "void main () {"
  "vec4 savedcolor = texture2D (saved, gl_TexCoord[0].st);"
  "vec4 currentcolor = texture2D (current, gl_TexCoord[0].st);"
  "gl_FragColor = vec4 (step (0.12, length (savedcolor - currentcolor)));"
  "}";

/* *INDENT-ON* */